A US woman who shot and killed her husband and two adult children before taking her own life is thought to have committed the shocking crime as a result of being ostracised from the religion she was raised in.

A federal judge sentenced a former Arkansas judge Wednesday to five years in prison — a stiffer punishment than prosecutors recommended — after he admitted giving young male defendants lighter sentences in return for personal benefits that included sexual favours.

Every time I tell a mate I’m doing a story on cryptocurrency, they invariably ask me the same two questions: should they invest their own hard-earned money, and which cryptocurrency will get them a Lamborghini/yacht/island quickest?

In a 60 Minutes online exclusive, reporter Liz Hayes quizzed Australian Prime Minister Malcolm Turnbull on his relationship with the unpredictable Twitter aficionado and US president Donald Trump ahead of their meeting at the White House Friday.

One thing is for sure: they will be followed by a most-polite and enormous media pack, keen to beam back to China gushing words and colourful footage of Mr Xi and Ms Peng on their travels Down Under, tagged on to the G20 Leaders Summit in Brisbane.

The significance of the visit is not lost on the Hobart business community, said Michael Bailey from the Tasmanian Chamber of Commerce and Industry.

"We do believe it could be transformational for the state," he told AAP.

"The cult around the president is incredible: what he eats, what he touches, where he goes is all carefully followed and becomes the desire of the entire Chinese community."

When Liberal premier Will Hodgman came to power in March his first diplomatic jobs was to travel to Beijing and hand deliver an invitation to Mr Xi.

"Our state's growing profile as a must-see tourism destination will gain an unprecedented boost with a visit from the Chinese president," Mr Hodgman said.

China is already Tasmania's number one international tourist market and it is also the state's largest trading partner, with merchandise and exports of some $610 million annually.

In Canberra on Monday the Tasmanian government will sign three memorandums of understanding - including one with the state-owned China Development Bank Corporation, the largest of its kind in the world - aimed to pave the way for new investment across industries such as agriculture, mining and tourism.

Mr Xi's visit to Tasmania coincides with an investment drive by the state government which will host more than 80 Chinese and international delegates including representatives from a number of Fortune 500 companies.

They will see a showcase of Tasmania's investment opportunities in agriculture, aquaculture, resources, tourism, education and Antarctic affairs.

Australian billionaire businessman Andrew Forrest is expected to attend the meetings which will culminate in a gala dinner on Tuesday night.

But all eyes will be on Mr Xi, 61, and Ms Peng, 51.

Ranked the third most powerful person in the world by Forbes magazine, Mr Xi's decision to visit Australia's southernmost state is quite a privilege.

And the accompanying Ms Peng - a folk singer known as much for her music, glamour and charity work as much as her marriage - is an added bonus.